The discussion of the background of the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge at the priority date of any of the claims.
An optical lens is typically made of plastic or glass material and generally has two opposite surfaces which co-operate with one another to provide a required corrective prescription. When the positioning or shape of one of these surfaces with respect to the other is inaccurate, optical errors can be created.
Optical lenses, and in particular ophthalmic lenses, require very high quality manufacturing process in order to obtain high quality optical lenses.
A lens manufacturing process comprises a great number of steps. Considering the overall quality requirement, a slight quality deficiency in one of the steps of the manufacturing process can have a great impact on the overall quality of the manufactured optical lens.
Although controlling the quality of the produced lenses is a complex task, lens manufacturers need to control the quality of the produced lenses, at least to check the conformity of the produced lenses with quality standards.
When a produced lens does not meet the quality requirements of the standard, the lens is set aside and a new lens is produced.
Producing lenses that are finally set aside is time consuming and costly for the lens manufacturer. Therefore, there is a general need for reducing the number of produced lenses that do not meet the quality requirements.
Quality deficiency of a produced lens is most of the time linked to either an operator deficiency or at least one manufacturing parameter of one of the manufacturing device that is incorrect.
Considering the number of operator interventions, the number of manufacturing parameters involved in an optical lens manufacturing process and that almost each produced lens is unique, it is very difficult for a lens manufacturer to properly identify the origin of the quality deficiency he may observe for a specific lens.